Principle Terrestrial Biomes - Annotated Bibliography Example

?Bawa, Kamajlit S. and S. Dayanandan. “Global Climate Change and The Tropical Rain Forest” Northeastern Naturalist 6.4 (1999 473-485. This is a journal article that covers the Tropical Rain Forests Biome. The article begins by explaining how incredibly important the genetic density of the tropical rain forests, not just for ecological and conservation purposes, but for humans as well. The authors argue that the genetic diversity of trees, for instance, is “vital for the continued flow of goods and services from forests ecosystems to meet present and human needs” (473). The authors also stress that tropical rain forests have a level of genetic density unseen in other parts of the world, and there are many specific niches un-known elsewhere, so this biome might be particularly vulnerable to any kind of climate change. The article “Global Climate Change and The Tropical Rain Forest” then goes on to examine different factors that could result from climate change that would inevitably lead to a reduction in the genetic diversity of the tropical rainforests. The principle culprits, the authors say, are “deforestation, forest fragmentation, and forest degradation” (474), which leads to the “extinction of genetically unique populations, promoting inbreeding, and disrupting gene flow” (475). The authors then go on to a thorough examination of the theoretical effects climate change might have in a much more specific way, outlining the particular process involved and detailing exactly how it could lead to a disruption in genetic diversity. These specific effects are grouped into major categories divided by the amount of individuals affected, ranging from “ecosystem level effects” through to “population level effects” (476, 477). This article does a good job describing the different systems that could be affected by climate change in very specific ways, and using previous research to speculate on what could be happening now and might happen in the future, but the bottom line is that this article is mostly a call for further research so the effects of climate change on rain forests can be better understood. Dauber, Jens and Volkmar Wolters. “Colonization of temperate grasslands by ants.” Basic and Applied Ecology 6 (2005): 83-91. This article focuses on the temperate grasslands, and examines and populations in them. It looks at a natural experiment occurring in a small region of Germany, where an area of grassland is persistently expanding by removing other obstacles to it such as human habitation. The exact dates that these obstacles were removed is well known, so know exactly how old the grasslands are, which is rare when studying ecological succession. They use this knowledge to examine the different species of ant which colonize the grassland once the grassland begins to grow. It uses simple sampling techniques to examine the populations of a wide variety of different types of ants at different stages of grasslands development, and the techniques used and data collected both seem extremely reliable. The research team found that in younger grasslands, there were a wide variety of different species that changed from individual patch of grassland to individual patch of grassland, because the initial populations were mostly dependent on the random chance of an individual or group from that species wandering into the grassland accidentally. They found, however, that as the grasslands matured and when studying older grasslands this initial diversity and wide range of species disappears, to be replaced with a more predictable group of species. This suggests that the initial distribution of species has no impact on the eventual one, and that a number of highly successful species of ants will consistently outperform other species in this kind of grassland. Gewin, Virginia. “Planting temperate forests won’t temper global warming” Frontiers in Ecology and the Environment 5.1 (2007): 6. This article details the effects that temperate rainforests might have on global warming. One of the most interesting aspects of this article is that it creates a clean distinction between carbon emissions, carbon sinks and global warming, noting that there are things that can be carbon sinks but not have any significant impact on global warming. The central thesis of this article is that new and emergent models of global must surpass old ones, which did not include “physical dynamics” of heating and cooling the planet (6), for instance reflection or absorption of radiation from the sun, because such dynamics have such a propensity for causing uncertainty in the modeling. In the case of temperate forests, however, physical dynamics must be considered, Gewin argues. She says there is significant evidence that the expansion or reduction of the amount of temperate forests has never had a significant impact on climate in any part of recorded history, and that this is probably due to the fact that temperate forests have dark-coloured foliage, and thus actually absorb a great amount of the heat coming from the sun, which neutralizes the carbon-sinking properties of a temperate rainforest (6). This most persuasive and interesting part of this article is its dissection of the politics surrounding arguments such as this. The author acknowledges that forests are good for the environment, and that it is understandable that other environmentalists might be afraid that this kind of argument could be used by anti-environmentalists to block reforestation projects and other such endeavors. But the author also argues that it is important for policy makers not to rely on initiative such as reforestation to fight global warming when there is evidence that these initiatives might not have an benefit, and that this could persuade policy makers to take a more radical look at addressing the real problems of global warming: “energy consumption” (6). Grace, John, Jose San Jose, Patrick Meir, Heloisa S. Miranda and Ruben A Montes. “Productivity and carbon fluxes of tropical savannas.” Journal of Biogeography 33.3 (2006): 387-400. This is a journal article that covers the tropical savanna biome, and relates tropical savanna productivity to savannas’ role in the global carbon cycle. It provides a relatively general overview, and attempts to “estimate the local and global magnitude of carbon fluxes between the savanna and the atmosphere” so that their significance to the global carbon cycle can be better understood (387). The article also seeks to estimate the usefulness of savannas in the fight against global warming, and to compare their productivity to other biomes. The article opens with a literature overview demonstrated the sources for the data used – the researchers in this case did no on the ground research, and so only data from outside sources were used, including national reports (389). This could be a problem as it does not provide for directly comparable data, as many of the field teams used different techniques for gathering and interpreting the data – furthermore, this article uses reports from a wide variety of areas, including Africa, Australia, India and South America, so there is a chance of bias, especially in the case of national reports. Upon studying the data, the authors found that tropical savannas were more productive than one might think, with their productivity being roughly equivalent to rainfall, which one would expect, with rain being the most limited resource for plants in the savanna ecosystem (394). The authors also speculated that if they were protected from fires and grazing, they would be even better carbon sinks than they already are (397), though this is a somewhat dubious prospect, as protection from natural fires might lead to denser energy storage and even worse infernos in the future – protection from human controlled grazing, however, makes a great deal of sense. The article finally concludes that loss of savannas world-wide is of significant detriment to the fight against global warming, because savannas can provide such important carbon sinks. Keeley, Ron. “Determinents of postfire succession and recovery in Mediterranean-climate shrublands of California.” Ecological Applications 15.5 (2005): 1515-1534. This is an article that covers the mediterannean shrub biome. It focuses on the fact that mediterannean shrub climates, with their high aridity and relatively low, small, dense population of plants are uniquely vulnerable to fires, and that fires occur as a natural part of the development of shrub lands. This article’s main research focus is on how shrub lands recover after a fire, and it tries to examine issues like which species grow best post fire, whether or not shrub lands ever return to exactly the same ecological position they held prior to the fire burning, and, if they do, how long the process tended to take. The author studied reports from sources like the US Geological Survey, the US Parks service, as well as other sources to help determine the kind of plants that tended to succeed best in post-fire environments, and what, if any human management should be applicable following a fire in shrubland. There tended to be a great deal of colonizing species, that is, species not originally from the shrub ecosystem, that would begin growing immediately post-fire: mediteranean shrubs are apparently not the best suited to quickly growing in post-fire situations. Eventually, however, the author found that the colonizing species tended to be out-competed by indigenous ones. They made up successively lower and lower percentages of the biomass following the fire, but never completely gave up their foothold, still being present in notable (but still relatively small) percentages at the end of a five year study. All this led the author to the conclusion that shrub ecosystems tended to withstand fire relatively well, and only in the cases of severe invasion by colonizing non-local species should human intervention occur. Skre, Odvar, Robert Baxter et. al. “How will the Tundra-Taiga interface respond to climate change?” Ambio 12 (2002): 36-47. This is an article on the tundra biome, and especially on the interaction between it and the biome that surrounds it, the northern forests (another article about the northern forests exclusively is annotated below). The basic question is how will the line dividing the tundra, which is the northern-most biome, and the taiga, which is the biome filled with northern forests that surround it, change over the course of global warming. This article claims that the traditional thinking would lead to the assumption that the taiga would encroach farther and farther upon the tundra (37), because the main determinant of where the tree line is (which separates the tundra from the taiga) is the fact that temperatures are too low in areas of tundra for those trees to survive. The article found, however, that there is a significant amount of durability to the current tree-line, and that it exists where it is in each individual locale for a variety of reasons, including local water cycles, forest evolution and so on, and not solely temperature (39). This means that it could be far more stable than people would not imagine, and might actually stay in place even with a significant warming of the planet, because temperature is not the only determinant of the presence of the tree-line. The author also notes that it is possible for localized cooling effects to occur as a consequence of global warming (for instance, if the gulf stream changes behavior) and this could possible even lead to the tundra pushing south into areas currently considered taiga. Though the only determinant of the taiga-tundra interchange is not temperature, it is simply true that trees cannot survive once the temperature dips too low, so it is much easier to model how the tree line will change do to cooling effects than warming ones. Schlesinger, William H, Jayne Benlap and Giles Marison. “On carbon sequestration in desert ecosystems” Global Change Biology 15 (2009): 1488-1490. This article covers the desert biome, again with an eye towards climate change and the role the ecosystem plays as a carbon sink. This article focuses on the fact that there has been a great deal of media attention on the role of deserts as a possible carbon sink, given recent findings based on gas exchange measurements which seem to indicate that the uptake of carbon in deserts might rival that of much more robust ecosystems, such as forests (1488). This article summarizes a wide array of studies on the carbon uptake of deserts using a variety of different measurements, with the goal of demonstrating that the reports of extraordinarily high uptake might be misleading, and that deserts are possibly not as good a sink as they would seem to suggest. The fundamental problem with these reports, according to the authors, is that they do not match actual measurements taken on the ground. The authors outline a series of studies which examine the amount of carbon in desert ecosystems, including carbon dissolved in water, in the ground, as well as carbon in the biomass of plants (1488). They find that all of these sources are most certainly not storing the amount of carbon that was suggested by gas exchange studies, so something may be wrong. The simplest explanation is simply that gas exchange measurements are not an effective measurement for this type of ecosystem (1489). The authors note, however, that it could be possible that the studies of gas exchanges only covered a three year span, and that it could be that there was a short-lived but significant uptick in carbon storage in that time period, or that the carbon uptake measurements were accurate, but that there were unknown sources of carbon loss that were not taken into account (1490). The data and arguments used in this article are both strong and convincing. Zhang, Ningning. “Dynamics of the larch taiga-peramfrost coupled system in Syberia under climate change.” Environmental Research Letters 6 (2011): 1-6. The larch taiga is a form of northern forest, so this article obviously focuses on the northern forest biome. It examines the changes that may occur to a particular kind of northern forest, the larch taiga of Siberia (taiga being another term for the northern forest biome) under extended climate change. It also underscores the importance of the taiga to the world’s water, energy and carbon cycles, predicting terrible consequences should the taiga be significantly affected by climate change. This article describes a system that occurs in the larch taiga, where the trees play an important role in melting the permafrost that occurs every year, and the permafrost’s melt thus provides the trees with enough water to fuel another year of growth (1). This is a cycle where both aspects of the process are completely interdependent – without the trees the permafrost might not melt, or might melt in significantly decreased quantities or much later in the year, and without the permafrost melting the trees would not have enough water to grow and survive and would likely die (4). This means that this ecosystem is likely very vulnerable to climate change, because a small shift could destabilize the process. Studies indicate that any significant climate change (for instance, greater than two degrees Celsius) would stop this process from working and would lead to a drastic shift in the composition of northern forests, moving from the taiga trees to darker trees more common of the temperate climes. This could have significant negative impact on the water cycle, which is dependent on the permafrost, which, as mentioned before, is dependent on the trees of the taiga and would probably not carry on in the same way if another type of tree becomes dominant. Read More